Unitary hub tape spool

ABSTRACT

An assembly comprises a substantially cylindrical tape winding surface and first and second flanges co-formed with the winding surface to form a unitary hub structure. The tape winding surface extends along an axis from a first end to a second end, and the first and second flanges extend radially from the first and second ends of the tape winding surface, respectively. The tape winding surface and the first and second flanges are co-formed of a unitary hub material having a Young&#39;s modulus of at least about one million psi.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/638,789, filed Apr. 26, 2012, entitled UNITARY HUB TAPE SPOOL, theentirety of which is hereby incorporated by reference herein.

BACKGROUND

Magnetic tape-based data storage systems provide secure, reliable,cost-efficient, and scalable data storage solutions for business,industry, and government service applications. In particular, magnetictape systems provide high data storage densities and capacity, withadaptable performance criteria suitable for a wide range of backup,archiving, and portable data storage needs.

Spool and cartridge-based magnetic tape systems combine these featuresin a practical, convenient, and accessible format for use in regulatedbulk storage environments. Tape spools and cartridges can also beemployed with a range of online, nearline, offline, and offsiteinfrastructures, in order to relay large datasets, ensure regulatorycompliance, and safeguard critical information while lowering datastorage costs and access time.

Across this wide range of magnetic storage applications, increasingengineering demands are continually made on the tape cartridge and spoolsystems, including not only the tape medium itself but also the spooland hub assembly. In particular, the spool and hub components aresubject to considerable compressive loading based on the tension in thetape pack windings, and this loading may vary significantly as afunction of temperature, humidity, and other environmental factors.

At the same time, tape cartridge and spool systems must also providehighly accurate speed and position control, for precision response tostart, stop, and read/write commands. These considerations placesubstantial design demands on the tape storage system, tape spool, andhub assemblies.

SUMMARY

Exemplary embodiments of the present disclosure include a tape hubassembly, a tape spool and a method for making a tape spool. The tapehub assembly may include a tape winding surface extending along an axisfrom a first end to a second end, with first and second flangesextending radially from the first and second ends, respectively. Thefirst and second flanges may be co-formed with the winding surface toform a unitary hub structure, and the unitary hub structure may beformed of material having a Young's modulus of at least about onemillion psi.

The tape spool may include a substantially cylindrical winding surfaceformed of a metal material, a first flange formed of the metal materialand extending radially from a first end of the winding surface, and asecond flange formed of the metal material and extending radially from asecond end of the winding surface. The winding surface, the first flangeand the second flange may be co-formed of the metal material to form aunitary hub structure.

The method may comprise forming a substantially cylindrical windingsurface extending along an axis from a first end to a second end,co-forming a first flange extending radially from the first end of thewinding surface, and co-forming a second flange extending radially fromthe second end of the winding surface. The winding surface, the firstflange and the second flange may be co-formed of a metal material havingan elastic modulus of at least about five million psi.

In any of the exemplary apparatus, tape spool and method embodiments, atape may be wound about the winding surface of the unitary hub, betweenthe first and second flange. The tape may impose a compressive load ofat least about 500 psi on the winding surface, and the winding surfacemay have a maximum radial deformation of less than about one mil, whensubject to the compressive load.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway view of a tape-based data storage system with aunitary hub spool assembly.

FIG. 2A is a perspective view of a spool assembly with a unitary hub andcoupling insert.

FIG. 2B is alternate perspective view of the spool assembly, showing acavity opposite the coupling insert.

FIG. 3 is a side view of the spool assembly, showing the tape-flangespacing.

FIG. 4 is a side view of the spool assembly, showing the couplinginsert.

FIG. 5 is a plot of radial deformation under compressive load, as afunction of hub position.

FIG. 6 is a plot of tension modulation test data for tape spools withdifferent hub compositions.

FIG. 7A is a plot of creep data for tape spools with different hubcompositions.

FIG. 7B is a plot of creep data as a function of hub material elasticmodulus.

FIG. 8 is a block diagram of a method for making a tape spool.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of magnetic tape-based data storagesystem 10 with spool assembly 12 and unitary hub 14. In this particularexample, data storage system 10 is configured as a cartridge-typemagnetic tape system with case or shell 16 and access 18 for tape-basedmagnetic medium 20. Tape medium 20 is wrapped on spool assembly 12 withunitary hub 14 for improved performance under tension and compressionloading, over a range of different environmental and operatingconditions.

Access 18 provides a gate, slide, window, or other access opening fortape medium 20. In some designs, including, but not limited to, LinearTape-Open (LTO) configurations, tape medium 20 is wound on a single reelor spool assembly 12, and leader pin 24 is provided for coupling to aseparate take-up reel inside the tape drive. Alternatively, a two-reelsystem 10 may be provided, with separate supply and take-up spoolassemblies 12, or an endless loop design may be used for tape medium 20and spool assembly 12.

Tape system 10 and spool assembly 12 may also include additionalfeatures such as spring-loaded or biased positioning elements in cavity26, switchable write protect tab 28 and memory chip 29, for example anRF (radio frequency) access memory device for system identification,configuration, formatting, tape usage, and other user data. These andother representative features of cartridge-based tape system 10 aredescribed in the following U.S. patent documents, for example asassigned to Imation Inc. of Oakdale, Minn., each of which incorporatedby reference herein: Rambosek, U.S. Pat. No. 6,345,779; Rambosek, U.S.Pat. No. 6,480,357; Ridl et al., U.S. Pat. No. 6,505,789; Morgan et al.,U.S. Pat. No. 6,968,459; Spychalla, U.S. Pat. No. 7,123,445; Rambosek etal., U.S. Pat. No. 7,170,708; Moses et al., U.S. Pat. No. 7,243,871; andBrown et al., U.S. Pat. No. 7,300,016.

Alternatively, spool assembly 12 and unitary hub 14 may also be providedindependently of or separately from case shell 16, and the othercomponents of cartridge-based data storage system 10. Magnetic medium ortape 20 also takes a variety of forms, including, but not limited to,digital data storage tape, audio and video tape for analog or digitalrecording, and other tape-based magnetic media formats including, butnot limited to, Linear Tape-Open, Scalable Linear Recording (SLR),T10,000, 9840, 9940, 3592, 3590, 3570, and other digital data standards.

As suitable for each of these applications, tape medium 20 may be formedby binding a magnetic coating to a substrate or base film, for example apolymer such as polyethylene terephthalate (PET) or polyethylenenaphthalate (PEN). A back coat may be applied to the surface oppositethe magnetic coating, for example silicon dioxide or carbon blackpigment particles (or both), with a blend of polymer resin ornitrocellulose binders to provide stiffness, reduce friction, dissipatestatic charge, and maintain uniform tape wind. It should be recognized,however, that the present invention may also be used with any suitabletype of tape or any suitable type of media, as desired, including, butnot limited to, audio, video and data-based media for digital and analogrecording.

In operation of recording system 10, tape medium 20 may imposesubstantial stresses and strains on spool assembly 12 and hub 14. Inparticular, tension loading on tape-based media 20 may generateconsiderable layer-to-layer pressure within spool assembly 12, resultingin significant compressive and other stresses on the winding surface ofhub 14. Changes in temperature, humidity, and other environmentalconditions can also cause the backer (substrate) and other components oftape medium 20 to expand or contract, generating asymmetric ortime-variable stress and strain components.

Stresses and strains on spool assembly 12 can lead to deformation of hub14, and contribute to tape wind issues including cinching, pack slip,spoking, windowing, and layer-to-layer adhesion. To reduce these effectsand improve performance, a substantially one-piece, unitary design canbe employed for hub 14, as described below, with a high rigidity, highstiffness hub material to provide increased service life and improvedreliability over a wider range of environmental and operatingconditions.

FIG. 2A is a perspective view of spool assembly 12 with unitary hub 14.Hub 14 includes an external winding surface on hub cylinder 30 andconstraint surfaces or flanges 32A and 32B, which may be co-formed withhub cylinder 30 to provide a unitary spool hub 14. Spool assembly 12 mayalso include insert 34 with additional features such as coupling element36 and magnetic washer or clutch element 38, as configured torotationally couple hub 14 to a tape drive or other mechanism forrotation of spool assembly 12.

Hub cylinder 30 forms a substantially cylindrical winding surface withfirst and second ends 30A and 30B arranged along rotational axis A. Tapemedium 20 may be wound onto the outer (winding) surface of hub cylinder30 between flanges 32A and 32B, forming a wound tape pack as describedabove.

Flanges 32A and 32B form generally parallel, substantially circular ordisc shaped surfaces, coaxially arranged along axis A of spool assembly12 and extending radially from first and second ends 30A and 30B of hubcylinder 30, respectively. Hub cylinder (or winding surface) 30 extendscoaxially along axis A, between first flange 32A and second flange 32B.

Hub cylinder 30 and flanges 32A and 32B are formed (or co-formed) of asubstantially unitary material, and provided as a single piece orunitary spool hub 14. Thus, unitary hub 14 may be provided as a “blank”spool, with necessary interchange items provided via insert 34, forexample by molding coupling element 36 and the other components ofinsert 34 from plastic or other material, and attaching magnetic washer38, as described below.

To reduce deformation under compressive loading, hub cylinder 30,flanges 32A and 32B, and the other components of unitary hub 14 areformed of a strong, durable, high stiffness material that is resistantto stress and strain. In some designs, for example, unitary hub 14 isformed of a metal injection molded (MIM) material such as magnesium, ora magnesium alloy. Other materials may also be used, including, but notlimited to, aluminum, magnesium, titanium, steel and nickel-based metalsand metal alloys, formed by one or more injection molding, powdermetallurgy, sintering, casting and rapid machining techniques.

Traditional machining methods may also be employed, either for finishmachining of unitary hub 14 or to manufacture hub 14 from a metalforging or other workpiece. In addition, one or more coatings can beapplied to reduce oxidation or corrosion, or to reduce friction betweenhub 14 and the cartridge case.

The unitary, stress resistant structure of hub 14 provides spoolassembly 12 with a more uniform tape winding surface along hub cylinder30, with substantially symmetric radius and other geometric propertiesfor improved winding of magnetic tape and other storage media. Flanges32A and 32B are also formed of substantially the same material as hubcylinder 30, providing improved dimensional stability and tighter (moreaccurate) spacing tolerance with respect to the storage medium, for lesstape rub and improved service life.

To provide unitary hub 14 with suitable levels of stiffness andresistance to stress and strain, materials with relatively high elasticor tensile modulus may be used. In particular, unitary hub 14 may beformed of a material with a particular elastic or tensile modulus, forexample a Young's modulus, shear modulus, bulk modulus, elasticity ormodulus of rigidity, where the modulus is selected to reduce deformationof the winding surface and deflection of flanges 32A and 32B whensubject to compressive stress or strain from multiple layers of amagnetic tape winding, or other operationally-induced stress or strain.

Depending on application, the material of unitary hub 14 may thus havean elastic or strain modulus of about a million psi (1 Mpi, or about 6.9GPa) or more, for example a metal or other material with a Young'smodulus of about 1.5×10⁶ psi (about 10 GPa) or more, or about 2.9×10⁶ toabout 3.6×10⁶ psi (about 20-25 GPa) or more. In one such application,the material of unitary hub 14 may have an elastic or strain modulus ofabout 5 million psi (about 34 GPa) or more, for example magnesium or amagnesium alloy (or other material) with a Young's modulus of about6.5×10⁶ psi, or about 45 GPa.

Alternatively, the material of unitary hub 14 may have somewhat higherelastic or strain modulus of about 7.3×10⁶ psi (about 50 GPa) or more,for example aluminum or an aluminum alloy (or other material) with aYoung's modulus of about 10×10⁶ psi (about 69 GPa), or titanium or atitanium alloy (or other material) with a Young's modulus of about15×10⁶ to about 17×10⁶ psi (about 105-120 GPa). In additional designs,the material of unitary hub 14 may have an elastic or strain modulusgreater than about 20×10⁶ psi (about 137 GPa), for example an iron orsteel alloy (or other material) with a Young's modulus of up to 29×10⁶psi (about 200 GPa) or more.

FIG. 2B is an alternate perspective view of spool assembly 12. This viewshows hub cavity 26 in second end 30B of hub cylinder 30, oppositecoupling insert 34 between flanges 32A and 32B.

As shown in FIG. 2A and FIG. 2B, inner portion 34A of insert 34 extendsaxially into flange 32A at inner radius r₁. Flange 32A extends radiallyfrom inner radius r₁ to first end 30A of hub cylinder 30, at inner hubradius r₂, and from inner hub radius r₂ at first end 30A of hub cylinder30 to outer radius R of spool assembly 12.

Hub cavity 26 is defined in second end 30B of hub cylinder 30, extendingradially from axis A of spool assembly 12 to inner radius r₂ of hubcylinder 30. Flange 32B extends from inner hub radius r₂ at second end30B of hub cylinder 30 to major radius R of spool assembly 12.

Hub cavity 26 extends axially along the inner surface of hub cylinder30, at inner hub radius r₂, from the inner surface of flange 32A atfirst end 30A to the outer surface of flange 32B at second end 30B.Thus, hub cylinder is closed at first end 30A and open at second end30B. This asymmetric configuration tends to result in non-uniform radialdeformation when hub 14 is subject to compression, but this effect canbe reduced by the rigid, unitary construction of hub 14, as describedbelow.

FIG. 3 is a side view of spool assembly 12, showing tape-flange spacinggaps d₁ and d₂ between tape medium 20 and flanges 32A and 32B of unitaryhub 14, respectively. Gaps d₁ and d₂ are defined between the innersurfaces of flanges 32A and 32B and the adjacent edges of tape medium20, in an axial direction along rotational axis A of spool assembly 12.

To maintain tape-flange spacing gaps d₁ and d₂ with low tolerance andhigh precision, flanges 32A and 32B are made of the same high strength,high elastic modulus material as hub cylinder 30, forming hub 14 as astrong, stiff, rigid, unitary structure as described above. Inparticular, this design reduces asymmetric radial deformation of hubcylinder 30 under compressive loading, and minimizes correspondingdeflections of flanges 32A and 32B. As a result, tape-flange spacinggaps d₁ and d₂ are maintained over a wide range of operating conditions,in order to prevent, reduce or minimize tape rub and other contactinteractions between tape medium 20 and flanges 32A and 32B of spoolassembly 12.

FIG. 4 is a side view of spool assembly 12, showing coupling insert 34.In this particular example, insert 34 includes coupling element 36 andmagnetic washer 38 for coupling hub 14 to a rotational drive, forexample a tape drive as described above.

Depending on application, coupling element 36 may be formed with notchesor teeth 40, for example from a thermoplastic or other polymer-basedmaterial, and attached to hub 14 by press fitting or using an epoxy orother bonding agent, or mechanical fasteners such as screws or pins.Alternatively, coupling element 36 may be molded or machined from thesame material as flange 32A, and formed as a unitary structure with theother components of spool hub 14. In additional examples, couplingelement 36 and spool hub 14 with flange 32A may be formed by an insertmolding technique.

Magnetic clutch or washer element 38 is formed of a magnetic material,in order to provide a magnetic coupling to effect the mechanicalattachment between coupling element 36 and a rotational drive mechanism.Depending on application, magnetic washer 38 may be press fit intomechanical coupling element 36, or attached with an adhesive ormechanical fastening. Alternatively, magnetic washer 38 may be formed asa unitary structure with the other components of spool hub 14, forexample by embedding a magnetic material into the powdered metal preformor by inserting magnetic washer 38 into the injection mold, and formingunitary hub 14 as a unitary structure with magnetic washer 38 embeddedwithin or inside unitary hub 14.

FIG. 5 is a plot of directional deformation as a function of hubposition. Radial deformation δ of hub cylinder 30 is plotted along thevertical axis, in arbitrary units. Axial hub position x is given alongthe horizontal, and defined in arbitrary units between first flange 32Aand second flange 32B.

As shown in FIG. 5, compressive loading results in asymmetric radialdeformation of the hub cylinder. In one particular example using amagnesium metal material for unitary hub 14, with a Young's modulus ofabout 45 GPa (about 6.5×10⁶ psi), a maximum radial deflection (δ_(max))of about 0.315 mil (about 8.0 μm) or less was observed, at a radialpressure of about 500 psi (about 3.4 MPa). For the same example,deflection δ was about 0.08 mil (about 2 μm) or less at the first(lower) flange (LF), adjacent the insert.

TABLE 1 Material Moduli and Radial Deformation Data Radial RadialEffective Radial Modulus Pressure Deformation Stiffness ×10⁶ psi GPa psiMPa mil μm ×10⁶ psi GPa 0.32 (UF) 2.2 500 3.4 4 (max) 100 0.108 0.7 0.74(LF) 5.1 0.6 (LF) 15 0.722 5.0 6.5 45 500 3.4 0.315 (max) 8 1.375 9.50.077 (LF) 2 5.653 39 2 14 500 3.4 1.772 (max) 45 0.244 1.7 3 21 500 3.41.182 (max) 30 0.366 2.5 4 28 500 3.4 0.886 (max) 23 0.489 3.4 5 34 5003.4 0.709 (max) 18 0.611 4.2 10 69 500 3.4 0.355 (max) 9 1.220 8.4

This compares favorably to existing multi-part hub designs with elasticor tensile moduli (e.g., Young's modulus) below about 10⁶ psi, as shownin Table 1. For these non-uniform designs, separate moduli are given forthe upper flange (UF) and lower flange (LF). The maximum radialdeflection is substantially greater at the same pressure, as compared tothe high stiffness, unitary design, for example about 4 mil (about 100μm) or more, with a radial deflection of about 0.600 mil (about 15 μm)or more at the lower flange.

Table 1 also provides results for a range of uniform unitary hubcompositions with representative material moduli between about 2×10⁶ psi(about 14 GPa) and about 10×10⁶ psi (about 69 GPa). These designs alsoexhibit maximum radial deflections below that of the existing multi-partdesign, for example between about 1.772 mil (about 45 μm) and about0.355 mil (about 9 μm).

FIG. 6 is a plot of tension modulation test data for tape spools withdifferent hub materials. Tension T is given on the vertical axes, inarbitrary units. Tape length or position L is given on the horizontalaxes, also in arbitrary units, based on the tape speed.

The standard reference or sample hub data in FIG. 6 were taken with anexisting multi-piece spool and hub configuration (plot 52), and theunitary hub data were taken with a single-piece, high strength unitaryhub (plot 54), as described above. The precision hub data were takenwith a customized multi-piece spool and hub assembly (plot 56), madewith high strength, high precision components for use on a test rig.

As shown in FIG. 6, tension T generally varies along tape length L, dueto a combination of tape winding effects, deformation of the spool huband contact (rubbing) against the flange surfaces or tape headcomponents. For the sample hub data (plot 52), the result is asubstantial variation in tension T throughout length L of the tape, witha signal-to-noise ratio of about 2:1 or about 3:1, based on a typicalobserved peak-to-peak variation of about 30-50%, as compared with theaverage tension T, or using the standard deviation over the mean.

The unitary hub data (plot 56) show a significant improvement over theexisting hub design. In particular, there is less asymmetric hubdeformation and corresponding flange deflection, resulting in fewerwinding effects and reduced tape rub. Thus, the rigid, unitary hub datahave a substantially higher signal-to-noise ratio, as compared to theexisting hub design, for example about 5:1 or greater, based on atypical variation of about 20% or less of the average tension T.

The precision hub data (plot 56) are similar to the unitary hub data(plot 54). Thus, the unitary hub design compares favorably with thesample (existing) hub design, and performs approximately as well as thecustom-design precision hub, at substantially reduced unit cost.

FIG. 7A is a plot of tape width or creep data for tape spools made withdifferent hub materials. Creep distribution measurements are shown onthe vertical axis, in arbitrary units, based on measurements of the tapewidth end of tape (EOT) position, near the hub, as compared to thebeginning of tape (BOT), outside the spool. The different hub materialsare distributed along the horizontal axis, including aluminum oraluminum alloy (Al), carbon fiber (CF), magnesium or magnesium alloy(Mg), and an existing design point of reference (POR), for example amulti-piece plastic or other polymer-based tape spool and hub assembly.

Creep is a stability parameter, and may be defined as the viscoelasticchange in tape width resulting from exposure to stress and strain,including tension and compression loading when wound on a tape spool.The creep distribution also depends on tape composition andenvironmental factors, including temperature and humidity. Across a widerange of operating conditions, however, changes in tape width are alsorelated to the effective stiffness of the tape hub, and selection of asuitable elastic or tensile modulus with a corresponding effectivestiffness can reduce or minimize creep (the change in tape width nearthe hub) in a wound tape pack.

TABLE 2 Creep Data (one-way ANOVA analysis) Mean Std Error Lower 95%Upper 95% Hub Type N (μm) (μm) (μm) (μm) Al 8 1.397 0.273 0.836 1.958Carbon 7 3.516 0.292 2.916 4.116 Fiber Mg 7 1.303 0.292 0.703 1.903 POR6 4.883 0.273 4.322 5.444

The creep distribution data show the change in tape width from the BOTposition to the EOT position for a wound tape pack. As shown in FIG. 7A,high stiffness hub materials such as aluminum (Al) and magnesium (Mg)are subject to substantially less creep than other designs, includingcarbon fiber (CF) and existing plastic or polymer (POR) designs. Thesignificance of these results is demonstrated via the Tukey-Kramermethod, based on a one-way analysis of the variance (ANOVA), as shown inTable 2.

FIG. 7B is a scatter plot of creep data as a function of hub elasticmodulus. The creep distribution measurements (vertical axis) are plottedagainst elastic or tensile modulus (e.g., Young's modulus) on thehorizontal axis, with both given in arbitrary units. These data weregenerated from tests on different tape media, holding the geometry ofthe hub assembly constant and changing the material modulus.

As shown in FIG. 7B, tape creep generally decreases as a function ofmodulus, or effective hub stiffness, based on the mechanical propertiesof the material from which the hub is formed. For modulus values aboveabout 10⁶ psi (about 6.9 GPa), for example, the hub cylinder and windingsurface are subject to substantially less radial deformation thanexisting designs, as described above, resulting in substantially lesscreep. The data also show a continued decrease in creep for materialswith elastic or Young's moduli above about 5×10⁶ psi (about 34 GPa),which includes hubs made from aluminum and magnesium materials.

The unitary, high stiffness design of spool hub 14 thus reduces creepdifferential, as defined between the beginning of tape and end of tapepositions. Unitary hub 14 also provides reduced variability in tension,as described above, providing a combination of greater transversedimensional stability and tension control, reducing run-out and lateraltape motion (LTM) for improved position error signal (PES) capability.

The use of a high stiffness, unitary hub design also provides a moreuniform winding surface, and allows for tighter manufacturing tolerancesand correspondingly more uniform hub geometry. Materials such asmagnesium and aluminum also provide higher effective radial stiffness,with better control of the hub geometry under compressive loading.Increased radial stiffness, in turn, reduces tape creep (or widthexpansion) and related (e.g., thickness) deformations of the tape whenwound onto the hub over time.

FIG. 8 is a block diagram of method 50 for making a tape spool, forexample spool assembly 12 as described above. Method 50 may include oneor more steps including, but not limited to, forming a substantiallycylindrical tape winding surface (step 52), forming a first flange with(step 54) extending radially from the first end of the tape windingsurface, and forming a second flange (step 56) extending radially fromthe second end of the tape winding surface.

Forming the tape winding surface (step 52) may be performed by forming asubstantially cylindrical hub component, extending axially from a firstend to a second end. The tape winding surface is defined as the radiallyouter surface of the hub cylinder.

Forming the first flange (step 54) may include forming the second flangeto extend from a radially inner diameter to the first end of the windingsurface, and from the first end of the winding surface to a major radiusof the tape spool. Forming second flange (step 56) may include formingthe second flange to extend from the second end of the winding surfaceto the major diameter of the tape spool.

The tape winding surface, the first flange, and the second flange may beco-formed as a unitary structure from a metal material, where the metalmaterial has an elastic modulus of at least about five million psi. Insome designs, the metal material comprises magnesium, aluminum, steel,another high stiffness metal with a high elastic or tensile modulus, orcombinations of these, as described above.

In some applications, method 50 includes co-forming the winding surfaceand the first and second flanges by injection molding (step 58) of themetal material. Alternatively, a powder metallurgy, sintering, rapidmachining process, traditional machining process, or combinations ofthese may be used.

In additional applications, method 50 includes attaching a couplingelement or rotational coupler (step 60) to the first flange. Thecoupling element comprising magnetic and mechanical coupling elementsfor rotational coupling of the tape winding surface to a tape drive. Infurther applications, method 50 includes winding a magnetic tape (step62) onto the winding surface.

In the foregoing description, various embodiments of the invention havethus been presented for the purpose of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise form disclosed. Obvious modifications or variations are possiblein light of the above teachings. The embodiments were chosen anddescribed to provide the best illustration of the principals of theinvention and its practical application, and to enable one of ordinaryskill in the art to utilize the invention in various embodiments andwith various modifications as are suited to the particular usecontemplated. All such modifications and variations are within the scopeof the invention as determined by the appended claims when interpretedin accordance with the breadth they are fairly, legally, and equitablyentitled.

1. An assembly comprising: a substantially cylindrical tape windingsurface extending along an axis from a first end to a second end; andfirst and second flanges co-formed with the winding surface to form aunitary hub structure, the first and second flanges extending radiallyfrom the first and second ends of the tape winding surface,respectively; wherein the tape winding surface and the first and secondflanges are co-formed of a unitary hub material having a Young's modulusof at least about one million psi.
 2. The assembly of claim 1, whereinthe unitary hub material has a Young's modulus of at least about fivemillion psi.
 3. The assembly of claim 1, wherein the unitary hubmaterial comprises an injection molded metal.
 4. The assembly of claim3, wherein the injection molded metal comprises magnesium.
 5. Theassembly of claim 3, wherein the injection molded metal comprisesaluminum.
 6. The assembly of claim 3, wherein the injection molded metalcomprises titanium.
 7. The assembly of claim 1, further comprising aninsert extending through an inner radius of the first flange, whereinthe insert is configured for rotational coupling to a tape drive.
 8. Theassembly of claim 7, further comprising a magnetic clutch componentcoupled to the insert.
 9. The assembly of claim 8, further comprising acavity extending from the axis to an inner radius of the winding surfaceat the second end.
 10. The assembly of claim 1, further comprising atape wound onto the winding surface between the first and secondflanges.
 11. The assembly of claim 10, wherein the winding surface isconfigured to have a maximum radial deformation of less than about 0.001inch between the first end and the second end when subjected to acompressive load of at least about 500 psi from the tape.
 12. A tapespool comprising: a substantially cylindrical hub defining a windingsurface; a first flange extending radially from a first end of the hub;a second flange extending radially from a second end of the hub; whereinthe hub, the first flange, and the second flange are co-formed of ametal material to define a unitary hub structure for the tape spool. 13.The tape spool of claim 12, wherein the metal material has an elasticmodulus of at least about five million psi.
 14. The tape spool of claim13, further comprising a tape wound onto the winding surface, whereinthe tape generates a compressive force of at least about 500 psi on thehub.
 15. The tape spool of claim 14, wherein the winding surface has amaximum radial deformation of less than about 0.001 inch when subject tothe compressive load.
 16. The tape spool of claim 12, furthercomprising: a coupling insert extending through an inner radius of thefirst flange; a magnetic washer coupled to the coupling flange; and acavity defined in the second end of the hub, the cavity extending froman axis of the tape spool to the second flange at an inner radius of thehub.
 17. A tape cartridge comprising the tape spool of claim
 14. 18. Amethod comprising: forming a substantially cylindrical tape windingsurface extending along an axis; co-forming a first flange with the tapewinding surface, the first flange extending radially from the first endof the tape winding surface; and co-forming a second flange with thetape winding surface, the second flange extending radially from thesecond end of the tape winding surface; wherein the tape windingsurface, the first flange and the second flange are formed as a unitarystructure from a metal material, the metal material having an elasticmodulus of at least about five million psi.
 19. The method of claim 18,further comprising co-forming the winding surface and the first andsecond flanges by injection molding of the metal material.
 20. Themethod of claim 19, further comprising attaching a coupling element tothe first flange, the coupling element comprising magnetic andmechanical coupling elements for rotational coupling of the tape windingsurface to a tape drive.